We reveal extraordinary electromagnetic properties for a general class of
uniaxially polarizable media. Depending on parameters, such metamaterials may
have wide range of nontrivial shapes of isofrequency contours including
lemniscate, diamond and multiply connected curves with connectivity number
reaching five. The possibility of the dispersion engineering paves a way to
more flexible manipulation of electromagnetic waves. Employing first-principle
considerations we prove that uniaxially polarizable media should be described
in terms of the nonlocal permittivity tensor which by no means can be reduced
to local permittivity and permeability even in the long-wavelength limit. We
introduce an alternative set of local material parameters including quadrupole
susceptibility capable to capture all of the second-order spatial dispersion
effects.Comment: submitted to Physical Review Letters; 5 pages, 5 figure